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Here be black holes

15 0 0
13.07.2020

There it floated, a luminous orange doughnut, glowing and fuzzy-edged, against a sea of darkness (Figure 1, below). Had it arrived without headline or caption, the world’s first ever image of a black hole might not have been recognised. Relayed across global news media, in April 2019, with appropriate fanfare and explanation, it caused the kind of stir you might expect of a scientific breakthrough. Prior to this, black holes had been ‘seen’ with the eye only through the images of science fiction. But now that we had a visual fix on black holes, an entity known only through abstract theory and via its gravitational effects on other bodies, were we any the wiser about them?

The image of M87* (the supermassive black hole at the centre of galaxy Messier 87) is the remarkable result of the efforts of researchers working with the international Event Horizon Telescope. At first sight so novel and game-changing, this unprecedented image is not the ‘photograph’ it appears to be. Instead it’s part of a long tradition of diagrammatically representing the heavens that stretches back at least as far as Galileo’s time-lapse sketches of sun spots, observed through a telescope at the turn of the 17th century. Galileo also made drawings of the Moon’s ridges and valleys, extrapolating imaginatively – from shifting light and dark patterns across the Moon’s phases – to surmise its physical features.

Perhaps more surprisingly, the black hole image has a lot in common with much earlier images of another sort of deep space, containing a different hidden entity: the sea monster. The Carta marina et descriptio septentrionalium terrarum (‘Marine Chart and Description of the Northern Lands’) was drawn in 1539 in Venice by Olaus Magnus, the Swedish geographer and titular archbishop of Uppsala, who was exiled in Rome during the early decades of the Reformation (main image, above, and Figure 3, below). With its array of octopuses, whales, walruses and other marine life in the North Atlantic, the chart is seemingly a world apart from the iconic image of M87*. Yet both are composite images derived from multiple sources, only some of which were visual. These sources were analysed in the mind and (via computers or mathematical instruments) compared with existing knowledge; the summary conclusions drawn from these mental excursions were then converted into visual images. These selective, compound, confected images – diagrams, in other words – enable us to ‘see’ in ways that are impossible in real life.

During the 15th and 16th centuries, when oceans were the spaces between worlds, marine animals, often so prodigious that they were termed sea monsters, were difficult to see and even harder to analyse, their very existence uncertain. Broadly construed, the history of space science is also a story of looking across and into the ocean – that first great expanse of space rendered almost unknowable by an alien environment. Deep space, like the deep sea, is almost inaccessible, with the metaphorical depth of space echoing the literal depth of oceans. These cognitive and psychic parallels also have an analogue in the practicalities of survival, and training for space missions routinely includes stints under water.

How can we grasp nature’s image and put it on a page? How do we judge the truthiness of images of nature? These questions are particularly challenging when it comes to images of the far reaches of galactic and oceanic space, which share a quality that we might call sensory distance. Such places exist at great remove: too small to discern with bodily senses (mere microns across, perhaps), too physically distant for instruments (outer space and ocean depths), or too inhospitable for sustained human presence. Visualising places of sensory distance requires distinctive approaches, not merely to collect information but also to interpret it, since the information gathered is patchy. In the absence of comprehensive and accessible information, acquiring knowledge about sea monsters and black holes calls for imaginative image-making.

Premodern chroniclers and naturalists had long attempted to describe, illustrate and classify distant wonders, from gold-digging ants to the Fountain of Youth. Such rare and unexpected marvels appeared to bend the rules of nature, and whether they were actual lifeforms, or phenomena assembled from piecemeal observations – such as the seemingly monstrous peoples at the edges of the Earth, or barnacle geese said to grow on trees – they were characterised by being difficult to observe in the field. Mariners had some direct, if limited, opportunities to witness deep-sea life. They might catch glimpses of whales surfacing for air from a whaling ship, or garner direct access to the bodies of whales and live to tell the tale. Landlubbers, however, were far removed from sea monsters in the flesh. If they lived near the sea, they might encounter extraordinary animals in fishermen’s catches, dashing to the beach if they got wind of a beached whale, or gazing at half-decayed specimens washed up on shore – drift whale.

A scene in a natural history compendium manuscript devoted primarily to marine life reveals people from many walks of life, some with animals in tow, gathering to gawk at the butchering of a whale beached near Antwerp in 1577 (Figure 2, below). This whale appears to still be alive: dark spray shoots out of its blowhole, its open eye gazes back at us. Fishermen had to work quickly to butcher such animals, before their flesh or precious oil spoiled. Scenes of whale dissections often show barrels nearby for collecting this liquid gold.

Viewers without access to a beached corpse had to make do with their imaginations and the testimonials of others, in........

© Aeon